BACKGROUND OF THE INVENTION
[0001] The present invention relates to variable diameter tubular structure, particularly
for a biomedical use.
[0002] As is known, in the biomedical field artificial ducts for conveying biologic liquids,
drugs and other medical devices therethrough are broadly used and include, for example,
either implantable or temporary ducts, to be used in hospital diagnostic or surgical
operations, in which it is necessary to convey a medical device from an operating
environment to a human body.
[0003] This operation is performed by a so-called introducer device, the function of which
is that of providing and holding in a patent condition a communication channel communicating
with the patient body, and usually held in the patient body through the overall duration
of the surgical operation or for a larger period.
[0004] The most common access ways are those to the haematic ducts (for example for performing
a vascular catheterization), the myocardium (for example for transapically locating
a cardiac valve) and, in general to other biologic ducts (for example for locating
biliary, urethral and ureteral stents).
[0005] Said introducer device comprises plastics material tubes either including or not
a sealing valve, and thereinto are introduced surgical devices and having an outer
diameter either less than or equal to the inner diameter of the introducer device.
[0006] Said introducer devices should provide a low inner friction to facilitate the conveying
therethrough of said medical devices from atraumatic tip and body portions, to prevent
patient tissues from being damaged, and should moreover have such a radial stiffness
as not to be bent under operating pressures, and further optionally including a sealing
valve and related side arm assembly for performing guiding withdrawing and/ monitoring
operations, in which said introducer device is introduced into the patient body by
a corresponding dilatator assembly, that is a tube having a tapering tip designed
for easily entering the patient tissues to provide the introducer and dilatator device
with a comparatively high radial strength.
[0007] At the end of the introducing operation, the dilatator assembly is withdrawn from
the patient body, while leaving therein only the introducer.
[0008] In some surgical operations it is necessary to change an introducer device and replace
it by another having either a larger or smaller diameter.
[0009] Up to now, the above operation would involve removing the introducer and locating
a new one.
SUMMARY OF THE INVENTION
[0010] Accordingly, the aim of the present invention is to provide such a tubular structure
having a variable diameter, that is a starting rest diameter which may be easily enlarged,
without applying any radial force, to recover said rest diameter as the structure
is released or is not subjected to an outer force.
[0011] Within the scope of the above mentioned aim, a main object of the invention is to
provide such a variable diameter tubular structure which may be particularly, though
not exclusively, used as an introducer body and for performing other biomedical operations,
for example to provide a permanent implant, a functional part of an artificial ventricle
or a sphincter assembly.
[0012] Another object of the invention is to provide such a variable diameter tubular structure
suitable to greatly improve related surgical or implant procedures and greatly reduce
the number of introducer devices to be used in said procedure, with a consequent reduction
of the operation, bleeding time and vessel or tissue traumatic stress.
[0013] Another object of the invention is to provide such a variable diameter tubular structure
allowing to greatly reduce the number of operations to implant different diameter
artificial channel elements.
[0014] Another object of the present invention is to provide such a variable diameter tubular
structure facilitating a closure of a puncture place.
[0015] Another object of the present invention is to provide such a variable diameter tubular
structure allowing to greatly reduce vessel wall traumas.
[0016] Yet another object of the present invention is to provide such a variable diameter
tubular structure which is very reliable and safe in operation.
[0017] According to one aspect of the present invention, the above mentioned aim and objects,
as well as yet other objects, which will become more apparent hereinafter, are achieved
by a biomedical variable diameter tubular structure,
characterized in that said structure comprises an extruded tube, which is longitudinally cut and then thermoformed
to define a longitudinal region having overlapping walls sliding with respect to one
another in a radial direction, said walls moving away as an article having a size
larger than a rest diameter of said tube passes through said tube.
[0018] According to a further aspect of the invention, said tube may be coupled to a resilient
sheath extending through the overall length of said tube.
[0019] Up to now in the medical field were not used polymeric materials having a shape memory
feature and a good structural stiffness, which characteristics, on the other hand,
were well known in steel and nickel-titanium alloy mesh patterns.
[0020] The present invention provides a plastics material tube having a variable diameter
which may be advantageously used in the medical field.
BRIEF DESCRIPTION OF THE DRAWINGS
[0021] Further characteristics and advantages of the present invention will become more
apparent hereinafter from the following disclosure of a preferred, though not exclusive,
embodiment of the invention, which is illustrated, by way of an indicative, but not
limitative, example in the accompanying drawings, where:
Figure 1 shows a cross sectional view of a variable diameter tube structure according
to the present invention respectively in a rest and in an expanded condition thereof;
Figure 2 shows, in cross-section, an embodiment of the inventive variable diameter
structure in a rest and expanded condition thereof;
Figure 3 is a further cross-sectional of another embodiment of the thermoformed tube
structure according to the present invention, including inward directed rough portions;
Figure 4 is a further cross-sectional view of another embodiment of the thermoformed
tube structure according to the present invention including outwardly directed rough
portions;
Figure 5 is a perspective view showing the guide, dilatator and introducer assembly
;
Figure 6 is a further perspective view showing the introducer device in a rest condition
thereof, without a dilatator engaged therein;
Figures 7 and 7a are further perspective views showing the introducer device with
an enlarged diameter, being enlarged by causing a larger diameter catheter to slide
therein;
Figure 8 is a cross sectional view of the tube including an outer tube sheath in a
rest condition thereof;
Figure 9 is a further cross-sectional view of the tube in an enlarged condition thereof,
the inner device being not shown;
Figure 10 is yet another perspective view showing a deformation of the introducer
with the device engaged therein and having an enlarged diameter only at a portion
of its overall length; and
Figure 11 shows an introducer device having a tip protected by a dilatator and a diameter
equal to or larger than that of the dilatator in a rest condition thereof.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0022] With reference to the number references of the above mentioned figures, the variable
diameter tubular structure according to the present invention, which has been generally
indicated by the reference number 1, is made starting from an extruded tube which
is properly modified and thermoformed and finally coupled to a resilient sheath assembly
2 extending through the overall length of the device body.
[0023] The expansion of the tube is achieved by providing a region 3 having radially sliding
walls, which are moved away as an article having a size larger than the rest diameter
of the tube is caused to pass through the latter.
[0024] For making the tube to a required or set contour, the following operations are performed:
- an extrusion of the tube with a set thickness and diameter, for example a thickness
of 0.5 and a diameter of 6 mm;
- a longitudinal cutting of the tube;
- an overlapping of the two tube open portions to a tube rest diameter, for example
5 mm, with a proper thermoforming of thus achieved contour.
[0025] Thus, by the above operations, a tube is achieved having an inner rest diameter corresponding
to a minimum target diameter and which may be easily enlarged.
[0026] A preferred configuration or embodiment of the extruded and thermoformed tube is
shown in figure 1, in which the tube has a variable thickness and the two open flaps
or edges thereof, indicated by the reference numbers 4 and 5, are smugly overlapped
thereby providing a precise thickness of said tube in its minimum diameter configuration.
[0027] Another similar solution, but with the tube having an eccentric thickness, is shown
in figure 2.
[0028] The tube contour may also be of the type shown in figures 3 and 4, wherein the tube
is extruded to or with an even thickness, the movable flap or tube portions being
overlapped, and the assembly being then thermoformed to provide a non linear contour
or profile, including rough portions which may be directed either inward and/or outward
depending on the thermoforming process.
[0029] Because the tube is extruded to a small thickness, for example 0.1 mm, said rough
portions will be very small and generally acceptable.
[0030] The material forming the variable diameter tubular structure according to the present
invention is preferably polyamide, PTFE or PE.
[0031] To insulate the tube inside with respect to the encompassing environment, for example
with respect to arterial blood, a resilient membrane 2 is applied to the tube contour.
[0032] Advantageously, for facilitating the operation, said membrane 2 is extended through
the overall length and profile of said tube, said membrane 2 being made of a polyurethane
material and being applied to the tube in a tube rest diameter condition by a dipping
coating method.
[0033] If desired, said membrane 2 may also be made by extruding and glueing operating steps.
[0034] A primer coating and other surface treatments may also be used.
[0035] The thus made tube, accordingly, will comprise two tube layers: a stiffener layer,
providing the tube duct or lumen, and a more resilient one, preventing the sliding
tube portions from detaching and communications between the tube inner lumen and outer
environment from occurring.
[0036] The tube, on the other hand, may be easily enlarged by engaging a device having a
diameter larger than that the tube rest diameter therein.
[0037] A withdrawing of the inner device allowing the resilient membrane 2 to "recover"
to their starting conditions the tube movable portions, thereby the tube will return
to its rest diameter.
[0038] The finished tube lubricating property may be improved by suitable lubricating or
lining materials, of a type conventionally used in the medical field, thereby the
tube may be easily used as a tube body for an introducer device.
[0039] In such an application, a proximal part of said tube is sealed to a valve 8 holding
said tube in its desirable maximum diameter condition.
[0040] If the tube is used to make an introducer, then it is necessary to provide a tube
tip 9 tapering to the dilatator, thereby preventing it from rubbing against the tissues
traversed thereby.
[0041] This result may be achieved by properly thermoforming the tip region of the tube.
[0042] Moreover it is preferred to provide a proper adhesion between the two tube layers,
the tip being in this case made of the stiffener layer only.
[0043] The inventive tube has advantageously a very small wall thickness, and may be enlarged
in a "modulable" and adjustable manner, that is in a non permanent manner through
the overall length thereof, while having a very low cost.
[0044] The variable tubular structure according to the present invention may be further
advantageously used to make a vascular introducer device body, as indicated by 100
in the drawing figures.
[0045] In this case, the tube will have a tube end fitted to a holding valve 8 having a
side arm 10 and an atraumatic blunted tip 9, the valve being a haemostatic valve comprising
a stiff fitting including a silicone diaphragm insulating the outside and inside of
the vessel, but allowing medical devices to pass therethrough, said silicone diaphragm
being precut, for example in the form a central star, the cuts snugly adhering to
the device passing therethrough.
[0046] In such a construction, the valve will be properly calibrated for allowing devices
having a maximum target diameter, for example of 7 mm, to easily pass therethrough.
[0047] The tube fitted to the valve, accordingly, will be opened to a target maximum diameter
of 7 mm, whereas the remaining portion of the introducer body will have the target
minimum diameter for example of 5 mm.
[0048] The introducer, accordingly, will have, at said valve, a diameter transition conical
region 11.
[0049] The vascular introducer 100 is engaged in the vessel through the patient tissue and
vessel wall, by a well known Seldinger's procedure, in which the vessel is punctured,
the guide engaged therein and then the introducer device preassembled on a dilatator
being further engaged.
[0050] The introducer device may be used in a like manner, by using a dilatator corresponding
to the minimum target diameter, for example of 5 mm.
[0051] Such a dilatator is a commercially available one, as well as the other conventionally
used devices.
[0052] Figure 5 shows the guide + dilatator + introducer in an assembled condition thereof.
[0053] Figure 6 shows the introducer device in a rest condition thereof, without any dilatator
engaged therein.
[0054] The introducer being then enlarged to the larger diameter, for example a maximum
diameter of 7 mm, by causing a catheter to slide therethrough, said catheter having
a larger diameter, as is shown in figures 7-9.
[0055] A further advantage of the structure according to the present invention is that it
does not require the use of a second dilatator.
[0056] Yet another advantage is that the enlargement of the introducer and, accordingly,
of the tissues therethrough said introducer passes, is limited in the time and performed
only as it is necessary.
[0057] Actually, the introduced device may have a larger diameter only at a portion of its
overall length.
[0058] In this case the introducer is deformed as shown in figure 10.
[0059] If it is desired to achieve a channel having a larger permanent diameter, that is
a diameter larger than the rest diameter, it is preferred to restrain the tube by
engaging therein a second tube.
[0060] Since the resilient membrane may cause problems related to the introducer tip tapering
and, accordingly, make the introducer making method expensive, it is possible to provide
a substantially truncated introducer tip and use a dilatator having a modified tip
adapted to "protect the tissue against the introducer tip portion to be withdrawn
owing to the introducer tube elastic feature.
[0061] In this case the dilatator will have a maximum diameter either larger than or equal
to the introducer rest diameter, and less than the enlarged introducer diameter, as
shown in figure 11.
[0062] The variable diameter tubular structure according to the present invention is susceptible
to several modifications and variations, all coming within the inventive idea scope.
[0063] If desired, the tube may also not be lined by a resilient membrane, for example for
a use in a dry environment, to prevent any material infiltration problems from occurring.
[0064] Moreover, the resilient membrane, instead of being arranged outside the tube, may
be also arranged therewithin, and may also be made by an independent making process
and easily sealed/glued to the tube.
[0065] The membrane, in particular, may also be made by an extruding process, as a first
or a second layer of the rigid tube.
[0066] The membrane may also be made by subjecting the tube to a dipping method in its as
extruded or it is both extruded and thermoformed condition.
[0067] The tube may also be coated by hydrophilic coating material on the inner and/or outer
walls thereof, to improve the sliding capability of devices engaged in the tube and/or
of the tube in the patient body.
[0068] The tube sliding parts may also have either a constant or variable thickness and
equal to or different from that of the tube.
[0069] The tube may also have either a constant or variable thickness, both in its longitudinal
and in its radial direction, and may be made by extruding or molding processes.
[0070] The membrane may be applied either to the overall profile of the tube or only to
the sliding portion thereof, or also to the overall tube or only to a tube portion.
[0071] It has been found that the invention fully achieves the intended aim and objects.
[0072] In fact, the invention has provided a variable diameter tubular structure greatly
improving surgical or implant procedures and greatly reducing the number of the introducer
devices to perform the surgical procedure and the operating and bleeding times and
the vessel or tissue traumas.
[0073] The structure according to the present invention allows moreover to greatly reduce
the number of operations to implant artificial different diameter channels, while
facilitating a closure of the puncture place with a consequent reduction of the vessel
wall trauma.
[0074] In practicing the invention, the used materials, as well as the contingent size and
shapes, can be any, depending on requirements.
1. A biomedical variable diameter tubular structure, characterized in that said structure comprises an extruded tube, which is longitudinally cut and thermoformed
to define a longitudinal region having overlapping walls sliding with respect to one
another in a radial direction, said walls moving away as an article having a size
larger than a rest diameter of said tube passes through said tube.
2. A tubular structure, according to claim 1, characterized in that said tube is coupled to a resilient sheath extending through an overall length of
said tube.
3. A tubular structure, according to claim 1, characterized in that said tube, in an extruded and thermoformed condition thereof, has a variable thickness
and two perfectly overlapped open flaps or edges thereof thereby providing a precise
thickness of said tube, where said tube is in a minimum diameter configuration thereof.
4. A tubular structure, according to claim 1, characterized in that said tube has an eccentric thickness.
5. A tubular structure, according to claim 1, characterized in that said tube is extruded to an even thickness, the movable flap or tube portions being
overlapped, and being thermoformed to a non linear profile including rough portions
either inward and/or outward directed.
6. A tubular structure, according to claim 1, characterized in that said tubular structure is made of a polyamide material.
7. A tubular structure, according to claim 2, characterized in that said sheath comprises a resilient membrane extending either through a part of a tube
length or through all the tube length, and all the tube profile, said membrane being
made of a polyurethane material and coated on the tube, in a rest diameter condition
of said tube, by a dipping coating method.
8. A vascular introducer device, characterized in that said device comprises an extruded tubular structure according to claim 1, said tubular
structure being longitudinally cut and thermoformed to define a longitudinal region
having overlapping walls which may slide in a radial direction with respect to one
another and to move away as an article having a size larger than a rest diameter of
said tubular structure passes through said tubular structure, said tubular structure
being coupled to a resilient outer sheath extending through a part or all a length
of said tubular structure, a proximal part of said tubular structure being sealed
to a valve adapted to hold said tubular structure in a maximum diameter condition
thereof, a tip of said tubular structure tapering toward a dilating device therefor.
9. An introducer device, according to claim 8, characterized in that said tubular structure has an end portion thereof coupled to a retaining valve with
a side arm and an atraumatic blunted tip, the valve being a haemostatic valve comprising
a stiff fitting including a silicone diaphragm insulating the outside and inside of
a body vessel while allowing a medical device to pass therethrough, said silicone
diaphragm being precut in the form of a central star by cuts snugly adhering to said
medical device.
10. An introducer device, according to claim 9, characterized in that said device comprises, near said valve, a diameter transition conical region.
11. An introducer device, according to claim 8, characterized in that said tubular structure is clamped by engaging therewithin a second tubular structure.
12. An introducer device, according to claim 9, characterized in that said introducer device has a truncated tip, said medical device including a dilatator
element having a removable tip portion adapted to protect body tissues against said
introducer device truncated tip.